1 /*
2 * linux/kernel/time.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * This file contains the interface functions for the various
7 * time related system calls: time, stime, gettimeofday, settimeofday,
8 * adjtime
9 */
10 /*
11 * Modification history kernel/time.c
12 *
13 * 1993-09-02 Philip Gladstone
14 * Created file with time related functions from sched.c and adjtimex()
15 * 1993-10-08 Torsten Duwe
16 * adjtime interface update and CMOS clock write code
17 * 1995-08-13 Torsten Duwe
18 * kernel PLL updated to 1994-12-13 specs (rfc-1589)
19 * 1999-01-16 Ulrich Windl
20 * Introduced error checking for many cases in adjtimex().
21 * Updated NTP code according to technical memorandum Jan '96
22 * "A Kernel Model for Precision Timekeeping" by Dave Mills
23 * Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
24 * (Even though the technical memorandum forbids it)
25 */
26
27 #include <linux/mm.h>
28 #include <linux/timex.h>
29 #include <linux/smp_lock.h>
30
31 #include <asm/uaccess.h>
32
33 /*
34 * The timezone where the local system is located. Used as a default by some
35 * programs who obtain this value by using gettimeofday.
36 */
37 struct timezone sys_tz;
38
39 /* The xtime_lock is not only serializing the xtime read/writes but it's also
40 serializing all accesses to the global NTP variables now. */
41 extern rwlock_t xtime_lock;
42
43 #if !defined(__alpha__) && !defined(__ia64__)
44
45 /*
46 * sys_time() can be implemented in user-level using
47 * sys_gettimeofday(). Is this for backwards compatibility? If so,
48 * why not move it into the appropriate arch directory (for those
49 * architectures that need it).
50 *
51 * XXX This function is NOT 64-bit clean!
52 */
sys_time(int * tloc)53 asmlinkage long sys_time(int * tloc)
54 {
55 struct timeval now;
56 int i;
57
58 do_gettimeofday(&now);
59 i = now.tv_sec;
60 if (tloc) {
61 if (put_user(i,tloc))
62 i = -EFAULT;
63 }
64 return i;
65 }
66
67 /*
68 * sys_stime() can be implemented in user-level using
69 * sys_settimeofday(). Is this for backwards compatibility? If so,
70 * why not move it into the appropriate arch directory (for those
71 * architectures that need it).
72 */
73
sys_stime(int * tptr)74 asmlinkage long sys_stime(int * tptr)
75 {
76 int value;
77
78 if (!capable(CAP_SYS_TIME))
79 return -EPERM;
80 if (get_user(value, tptr))
81 return -EFAULT;
82 write_lock_irq(&xtime_lock);
83 vxtime_lock();
84 xtime.tv_sec = value;
85 xtime.tv_usec = 0;
86 vxtime_unlock();
87 time_adjust = 0; /* stop active adjtime() */
88 time_status |= STA_UNSYNC;
89 time_maxerror = NTP_PHASE_LIMIT;
90 time_esterror = NTP_PHASE_LIMIT;
91 write_unlock_irq(&xtime_lock);
92 return 0;
93 }
94
95 #endif
96
sys_gettimeofday(struct timeval * tv,struct timezone * tz)97 asmlinkage long sys_gettimeofday(struct timeval *tv, struct timezone *tz)
98 {
99 if (tv) {
100 struct timeval ktv;
101 do_gettimeofday(&ktv);
102 if (copy_to_user(tv, &ktv, sizeof(ktv)))
103 return -EFAULT;
104 }
105 if (tz) {
106 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
107 return -EFAULT;
108 }
109 return 0;
110 }
111
112 /*
113 * Adjust the time obtained from the CMOS to be UTC time instead of
114 * local time.
115 *
116 * This is ugly, but preferable to the alternatives. Otherwise we
117 * would either need to write a program to do it in /etc/rc (and risk
118 * confusion if the program gets run more than once; it would also be
119 * hard to make the program warp the clock precisely n hours) or
120 * compile in the timezone information into the kernel. Bad, bad....
121 *
122 * - TYT, 1992-01-01
123 *
124 * The best thing to do is to keep the CMOS clock in universal time (UTC)
125 * as real UNIX machines always do it. This avoids all headaches about
126 * daylight saving times and warping kernel clocks.
127 */
warp_clock(void)128 inline static void warp_clock(void)
129 {
130 write_lock_irq(&xtime_lock);
131 vxtime_lock();
132 xtime.tv_sec += sys_tz.tz_minuteswest * 60;
133 vxtime_unlock();
134 write_unlock_irq(&xtime_lock);
135 }
136
137 /*
138 * In case for some reason the CMOS clock has not already been running
139 * in UTC, but in some local time: The first time we set the timezone,
140 * we will warp the clock so that it is ticking UTC time instead of
141 * local time. Presumably, if someone is setting the timezone then we
142 * are running in an environment where the programs understand about
143 * timezones. This should be done at boot time in the /etc/rc script,
144 * as soon as possible, so that the clock can be set right. Otherwise,
145 * various programs will get confused when the clock gets warped.
146 */
147
do_sys_settimeofday(struct timeval * tv,struct timezone * tz)148 int do_sys_settimeofday(struct timeval *tv, struct timezone *tz)
149 {
150 static int firsttime = 1;
151
152 if (!capable(CAP_SYS_TIME))
153 return -EPERM;
154
155 if (tz) {
156 /* SMP safe, global irq locking makes it work. */
157 sys_tz = *tz;
158 if (firsttime) {
159 firsttime = 0;
160 if (!tv)
161 warp_clock();
162 }
163 }
164 if (tv)
165 {
166 /* SMP safe, again the code in arch/foo/time.c should
167 * globally block out interrupts when it runs.
168 */
169 do_settimeofday(tv);
170 }
171 return 0;
172 }
173
sys_settimeofday(struct timeval * tv,struct timezone * tz)174 asmlinkage long sys_settimeofday(struct timeval *tv, struct timezone *tz)
175 {
176 struct timeval new_tv;
177 struct timezone new_tz;
178
179 if (tv) {
180 if (copy_from_user(&new_tv, tv, sizeof(*tv)))
181 return -EFAULT;
182 }
183 if (tz) {
184 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
185 return -EFAULT;
186 }
187
188 return do_sys_settimeofday(tv ? &new_tv : NULL, tz ? &new_tz : NULL);
189 }
190
191 long pps_offset; /* pps time offset (us) */
192 long pps_jitter = MAXTIME; /* time dispersion (jitter) (us) */
193
194 long pps_freq; /* frequency offset (scaled ppm) */
195 long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
196
197 long pps_valid = PPS_VALID; /* pps signal watchdog counter */
198
199 int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
200
201 long pps_jitcnt; /* jitter limit exceeded */
202 long pps_calcnt; /* calibration intervals */
203 long pps_errcnt; /* calibration errors */
204 long pps_stbcnt; /* stability limit exceeded */
205
206 /* hook for a loadable hardpps kernel module */
207 void (*hardpps_ptr)(struct timeval *);
208
209 /* adjtimex mainly allows reading (and writing, if superuser) of
210 * kernel time-keeping variables. used by xntpd.
211 */
do_adjtimex(struct timex * txc)212 int do_adjtimex(struct timex *txc)
213 {
214 long ltemp, mtemp, save_adjust;
215 int result;
216
217 /* In order to modify anything, you gotta be super-user! */
218 if (txc->modes && !capable(CAP_SYS_TIME))
219 return -EPERM;
220
221 /* Now we validate the data before disabling interrupts */
222
223 if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
224 /* singleshot must not be used with any other mode bits */
225 if (txc->modes != ADJ_OFFSET_SINGLESHOT)
226 return -EINVAL;
227
228 if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
229 /* adjustment Offset limited to +- .512 seconds */
230 if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
231 return -EINVAL;
232
233 /* if the quartz is off by more than 10% something is VERY wrong ! */
234 if (txc->modes & ADJ_TICK)
235 if (txc->tick < 900000/HZ || txc->tick > 1100000/HZ)
236 return -EINVAL;
237
238 write_lock_irq(&xtime_lock);
239 result = time_state; /* mostly `TIME_OK' */
240
241 /* Save for later - semantics of adjtime is to return old value */
242 save_adjust = time_adjust;
243
244 #if 0 /* STA_CLOCKERR is never set yet */
245 time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
246 #endif
247 /* If there are input parameters, then process them */
248 if (txc->modes)
249 {
250 if (txc->modes & ADJ_STATUS) /* only set allowed bits */
251 time_status = (txc->status & ~STA_RONLY) |
252 (time_status & STA_RONLY);
253
254 if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
255 if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
256 result = -EINVAL;
257 goto leave;
258 }
259 time_freq = txc->freq - pps_freq;
260 }
261
262 if (txc->modes & ADJ_MAXERROR) {
263 if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
264 result = -EINVAL;
265 goto leave;
266 }
267 time_maxerror = txc->maxerror;
268 }
269
270 if (txc->modes & ADJ_ESTERROR) {
271 if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
272 result = -EINVAL;
273 goto leave;
274 }
275 time_esterror = txc->esterror;
276 }
277
278 if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
279 if (txc->constant < 0) { /* NTP v4 uses values > 6 */
280 result = -EINVAL;
281 goto leave;
282 }
283 time_constant = txc->constant;
284 }
285
286 if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
287 if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
288 /* adjtime() is independent from ntp_adjtime() */
289 time_adjust = txc->offset;
290 }
291 else if ( time_status & (STA_PLL | STA_PPSTIME) ) {
292 ltemp = (time_status & (STA_PPSTIME | STA_PPSSIGNAL)) ==
293 (STA_PPSTIME | STA_PPSSIGNAL) ?
294 pps_offset : txc->offset;
295
296 /*
297 * Scale the phase adjustment and
298 * clamp to the operating range.
299 */
300 if (ltemp > MAXPHASE)
301 time_offset = MAXPHASE << SHIFT_UPDATE;
302 else if (ltemp < -MAXPHASE)
303 time_offset = -(MAXPHASE << SHIFT_UPDATE);
304 else
305 time_offset = ltemp << SHIFT_UPDATE;
306
307 /*
308 * Select whether the frequency is to be controlled
309 * and in which mode (PLL or FLL). Clamp to the operating
310 * range. Ugly multiply/divide should be replaced someday.
311 */
312
313 if (time_status & STA_FREQHOLD || time_reftime == 0)
314 time_reftime = xtime.tv_sec;
315 mtemp = xtime.tv_sec - time_reftime;
316 time_reftime = xtime.tv_sec;
317 if (time_status & STA_FLL) {
318 if (mtemp >= MINSEC) {
319 ltemp = (time_offset / mtemp) << (SHIFT_USEC -
320 SHIFT_UPDATE);
321 if (ltemp < 0)
322 time_freq -= -ltemp >> SHIFT_KH;
323 else
324 time_freq += ltemp >> SHIFT_KH;
325 } else /* calibration interval too short (p. 12) */
326 result = TIME_ERROR;
327 } else { /* PLL mode */
328 if (mtemp < MAXSEC) {
329 ltemp *= mtemp;
330 if (ltemp < 0)
331 time_freq -= -ltemp >> (time_constant +
332 time_constant +
333 SHIFT_KF - SHIFT_USEC);
334 else
335 time_freq += ltemp >> (time_constant +
336 time_constant +
337 SHIFT_KF - SHIFT_USEC);
338 } else /* calibration interval too long (p. 12) */
339 result = TIME_ERROR;
340 }
341 if (time_freq > time_tolerance)
342 time_freq = time_tolerance;
343 else if (time_freq < -time_tolerance)
344 time_freq = -time_tolerance;
345 } /* STA_PLL || STA_PPSTIME */
346 } /* txc->modes & ADJ_OFFSET */
347 if (txc->modes & ADJ_TICK) {
348 /* if the quartz is off by more than 10% something is
349 VERY wrong ! */
350 if (txc->tick < 900000/HZ || txc->tick > 1100000/HZ) {
351 result = -EINVAL;
352 goto leave;
353 }
354 tick = txc->tick;
355 }
356 } /* txc->modes */
357 leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0
358 || ((time_status & (STA_PPSFREQ|STA_PPSTIME)) != 0
359 && (time_status & STA_PPSSIGNAL) == 0)
360 /* p. 24, (b) */
361 || ((time_status & (STA_PPSTIME|STA_PPSJITTER))
362 == (STA_PPSTIME|STA_PPSJITTER))
363 /* p. 24, (c) */
364 || ((time_status & STA_PPSFREQ) != 0
365 && (time_status & (STA_PPSWANDER|STA_PPSERROR)) != 0))
366 /* p. 24, (d) */
367 result = TIME_ERROR;
368
369 if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
370 txc->offset = save_adjust;
371 else {
372 if (time_offset < 0)
373 txc->offset = -(-time_offset >> SHIFT_UPDATE);
374 else
375 txc->offset = time_offset >> SHIFT_UPDATE;
376 }
377 txc->freq = time_freq + pps_freq;
378 txc->maxerror = time_maxerror;
379 txc->esterror = time_esterror;
380 txc->status = time_status;
381 txc->constant = time_constant;
382 txc->precision = time_precision;
383 txc->tolerance = time_tolerance;
384 txc->tick = tick;
385 txc->ppsfreq = pps_freq;
386 txc->jitter = pps_jitter >> PPS_AVG;
387 txc->shift = pps_shift;
388 txc->stabil = pps_stabil;
389 txc->jitcnt = pps_jitcnt;
390 txc->calcnt = pps_calcnt;
391 txc->errcnt = pps_errcnt;
392 txc->stbcnt = pps_stbcnt;
393 write_unlock_irq(&xtime_lock);
394 do_gettimeofday(&txc->time);
395 return(result);
396 }
397
sys_adjtimex(struct timex * txc_p)398 asmlinkage long sys_adjtimex(struct timex *txc_p)
399 {
400 struct timex txc; /* Local copy of parameter */
401 int ret;
402
403 /* Copy the user data space into the kernel copy
404 * structure. But bear in mind that the structures
405 * may change
406 */
407 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
408 return -EFAULT;
409 ret = do_adjtimex(&txc);
410 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
411 }
412